By Will Stallard
County Extension Agent for Agricultural & Natural Resources

Corn silage can be a great feed, especially for growing cattle and milk cows. It can also be a feed with various quality problems. The difference between very good and fair is when it is cut and how it is stored.

The proper stage of harvest is determined mostly by the state of maturity of the corn plant. Highest dry matter digestibility and quality occurs when the silage is from 30 to 40 percent dry matter. Silage that is wetter than this has excessive runoff and seepage, which carries important nutrients with it. Silage over 40 percent dry matter does not pack well, thus more likely to have air pockets, resulting in mold growth and heating.

The best guide to plant moisture content is the stage of development of the grain. The location of this milk line in the kernel is a good guide to plant maturity. The desired stage is having the milk line about one-half of the way down the kernel. This corresponds to about 35 percent dry matter in the whole-plant silage. At this point the silage is ideal for good chopping, good pack, good quality and good performance by the cattle. Often letting the corn get too dry is a real problem as cattle can’t eat enough of it to get the feed value they need to milk or gain well. A few days of delay can cost you a lot of money. If you need help in determining the milk line, bring a few ears by the office and I’ll show you how to check them.

Corn silage must be stored in air-tight conditions to minimize spoilage. Anywhere that air contacts the surface of silage it deteriorates. Two critical steps in the process accomplish air-tight storage. One of those is to store silage in a structure that excludes as much air as possible. Upright silos must be free of cracks or other leaks. Horizontal silos are going to have a lot of exposure to the air just be their design. The main way to reduce this is to have the silo in a long, narrow shape with a narrow face exposed to the air. Silos that are very wide expose a lot more silage to the air. Silage removal should be planned so that a minimum of six inches of material is removed from the exposed surface every day during the feeding season.

The second critical step in excluding air from the silage is proper packing. With upright silos this is accomplished simply by the weight of the material itself. The weight of the silage material in a horizontal silo is not adequate to pack the pile tightly. This is accomplished by driving over the pile with a tractor to compress the material as it is being layered into the silo. Keep someone on the packing tractor and keep it moving.

The tighter the pack, the less spoilage you will have. Corn silage can also be stored in silage bags, which do a great job of excluding air and preserving the silage well. Be sure to check the bags frequently for rodent and bird damage and repair bags as needed.

In summary, it is fairly easy to make good corn silage. Once the crop is planted and growing, the key decision is timing of the harvest. Cutting corn for silage when it is around 35 percent dry matter, corresponding to the one-half milk line stage of maturity, results in a highly digestible feed material.

Collect samples of the corn silage as you harvest it. Keep it refrigerated or on ice until you are ready to have it tested. We can assist you with getting your silage tested for quality factors. Many of our local feed suppliers can also do the testing for you. After you get the results, I will be happy to help you develop a balanced feeding program for your livestock.

For more information on corn silage or any agricultural topic, contact Will Stallard, County Extension Agent for Agricultural & Natural Resources, 104 Metker Trail, Stanford, KY 40484 or at (606) 365-2447.